1. Field of the Invention
The present invention relates to a power supply for feeding power to a computer, and a control method of the power supply.
2. Description of the Related Art
Virtualization management is generally used for effective utilization of the resources of physical computers. The virtualization management uses the physical computers as virtual hosts. Each virtual host is configured to run one or multiple virtual machines (VMs) in emulation. In the virtualization management, a VM is sometimes migrated to a different virtual host depending upon the running situations of the VMs. Using a structure that allows flexible migration of a VM to any virtual host makes it possible to effectively utilize the resources of the physical computers.
Meanwhile, there are methods that use a power control device to reduce the power consumption of the physical computers (see Japanese Patent Application Publication No. 2008-269249, for example). In the method described in Japanese Patent Application Publication No. 2008-269249, the power control device collects the load statuses of systems, migrates a system to a given physical computer on the basis of the load statuses, and turns off the power of the unselected physical computer. By causing the power control device to perform both virtualization management and power management as described above, the power consumption of the physical computers can be expected to be reduced.
Meanwhile, a virtual system including virtual hosts and VMs may include a virtualization management server in some cases. The virtualization management server is configured to control the virtual hosts and the VMs of the virtual system. Such a virtualization management server is generally a physical server, and therefore the resources of the virtualization management server such as the number of CPUs and a memory are the same as the resources of the physical server. Accordingly, increasing or decreasing the resources of the virtualization management server requires increasing or decreasing the physical resources. However, there is a method in which the virtualization management server is run on a virtual host, and multiple physical servers are used to change the resources of the virtualization management server as needed (vmware, “Running VirtualCenter in a Virtual Machine,” [online], internet <URL: http://www.vmware.com/pdf/vi3_vc_in_vm.pdf> [searched on Jan. 7, 2011]).